Surface particle counters typically operate by using a scanner head that moves over the surface of the area of interest, pulling particles into the flow through a conduit. This conduit transports the particles to a counter. After being counted in the counter, the airflow is filtered and reutilized providing a stream of air in the scanner head meant to disturb the particles on the surface.
Typically, prior inventions have a conduit separates the scanner and counter. Therefore, the typical process for a particle-counting device involves particles passing through a scanner where the particles are then pulled and transferred through a conduit before being counted at the counter. After being counted, the particles are then moved by the fluid stream generated by the particle-counting device through a pump and then a filter, ultimately ending up back at the scanner where the particles are pulled again. This is shown in FIG. 1.
As we see in FIG. 1, a conventional scanner (1) is positioned close to a conventional surface (2). Blowing air (3) exits conventional scanner (1) and disburses particles from conventional surface (2) so that the particles are sucked through conventional scanner (1) through first tube (4) and into conventional housing (105). Conventional particle counter (6) receives the sucked particles from first tube (4) and counts the particles. The particles then travel to conventional pump (7) where some particles exit conventional housing (105); whereas other particles move from the conventional pump (7) to conventional filter (8). Most particles are trapped conventional filter (8) but the air in which they were traveling moves through second tube (9) and returns to conventional scanner (1) as blowing air (3).
One of the problems with this mechanism is the transport of particles from the surface to the particle counter. Because of the distance between the surface of interest and the particle sensor, there are particle transport issues that may result in loss of particles in such problematic manners as particles sticking to the transport tube and particle traps caused by gaps and dead space of the various fittings. This results in inaccurate readings from the particle counter. This problem becomes greater as the particle size increases. The present invention addresses this issue by combining the scanner element and the particle sensor into one apparatus. In this way, the present invention saves one significant step in the particle flow process. By effectively shortening the distance that particles must travel, the present invention fixes an important problem by avoiding the potential loss of particles before being counted.
U.S. Pat. No. 5,253,538 refers to a particle counting device comprising a scanner and a particle counter, however, the particles must first pass through the scanner and then a “plurality of tubes” before reaching the particle counter. This setup allows many places for particles to stick to before reaching the counter. The present invention aims to solve this problem by placing the particle counter directly near the scanner so that the particles do not have to pass through a plurality of tubes before being counted.